Morphology of the normal and arthritic glenoid.

The normal glenoid has a pear-shape aspect and is slightly retroverted. It has a variable orientation in the sagittal plane. The cartilage surface area corresponds to 28 % of the area of the humeral head with a radius of curvature greater than the humeral head. Mechanical properties are significantly higher at the center and posterior edge of the glenoid. With osteoarthritis, the glenoid becomes larger with a greater width and an increasing of the retroversion angle. The wear can be centric or excentric. Mechanical properties are significantly higher at the center and posterior edge of the glenoid.